JP6014680B2 - Laminated film and shield printed wiring board - Google Patents

Description

  The present invention relates to a laminated film, and more particularly to a laminated film for a shield film that shields electromagnetic waves from an electronic device or the like and a shield printed wiring board.

  2. Description of the Related Art Conventionally, shielded printed wiring boards in which a shield film is provided on a circuit board such as a flexible printed wiring board have been used in portable devices and personal computers for the purpose of suppressing noise and shielding electromagnetic waves to the outside.

  Such a shield printed wiring board is generally manufactured as follows. First, the shield film is coated on the cover film side of the laminated film in which the cover film (transfer target layer) is formed by coating the resin on one side of the separate film (transfer film) with a release layer. Formed. The shield printed wiring board includes a base member on which a ground wiring pattern and a signal wiring pattern are formed, and an insulating film laminated on the base member and exposing at least a part of the ground wiring pattern. It is formed by attaching a shield film to a plate and heating and pressing. The shield film has a conductive adhesive layer on the surface to be bonded to the printed wiring board, and the conductive adhesive layer is embedded in a portion where the ground wiring pattern of the insulating film is exposed during heat pressing. Thereby, the ground wiring pattern and the shield layer are electrically connected, and the electromagnetic wave shielding function is further improved.

As a release film such as a separate film used in such a manufacturing process, there are applications, for example, there are Patent Documents 1 and 2.
Patent Document 1 discloses a release film used in a prepreg press process at the time of producing a copper-clad laminate, in which a release layer is provided on one or both sides of a polyester foam film. Yes. Patent Document 2 discloses a release film having embossing, and the surface roughness (Rz: ten-point average roughness) of the embossing of the release film is 5 μm or more and 20 μm or less before the pressing step. There is disclosed a release film used in a circuit board pressing step, which is 2 μm or more and 8 μm or less later.

Japanese Patent Laid-Open No. 2002-1726 JP 2008-246882 A

  However, since Patent Documents 1 and 2 are used as a cushioning material in a circuit board pressing process, there is a possibility that sufficient adhesive force cannot be obtained because the release film of the release film is too peelable. . Also, in general, a separate film is formed of a single layer of resin, and depending on the conditions, shape followability with respect to a cover film to which the separate film is attached is reduced, so that the ground wiring pattern of the printed wiring board is insulated. When the portion exposed from the film has a small diameter, there is a problem that sufficient embedding of the conductive adhesive layer cannot be obtained.

  Then, this invention aims at providing the lamination | stacking film which can acquire favorable embedding property and workability, and can control appropriately the adhesive force with respect to the to-be-transferred layer of a transfer film.

The laminated film of the present invention has a crystallized inner resin layer and a crystallized outer resin layer laminated on one surface and the other surface of the inner resin layer, and at least one of these outer resin layers. A transfer film having a concavo-convex pattern formed on the outer surface thereof, and a transfer layer on which the transfer pattern is formed by being detachably laminated on the outer surface of the transfer film on which the concavo-convex pattern is formed. And the inner resin layer is made of polyethylene terephthalate, and the outer resin layer is made of polybutylene terephthalate.

According to the said structure, the outer side resin layer formed of the polybutylene terephthalate is laminated | stacked on both surfaces of the inner side resin layer formed of the polyethylene terephthalate by the transfer film. Thereby, since the followability of the transfer film with respect to the shape change of the layer to be transferred is improved, good embedding can be obtained. In addition, since the inner resin layer formed of polyethylene terephthalate is laminated, the outer resin layer is formed by the inner resin layer even when the outer surface of the outer resin layer expands or contracts in the surface direction due to a change in temperature or the like. Deformation is reduced. Furthermore, because the outer resin layer is laminated on both sides of the inner resin layer, the outer surface of the outer resin layer can offset the forces that the outer surface tries to expand and contract in the surface direction, reducing the deformation of the transfer film. Is done. Therefore, when the shield film having the laminated film of the present invention is bonded to a printed wiring board and heated and pressed, it is possible to prevent the occurrence of problems due to the deformation of the laminated film.
Furthermore, by forming an uneven pattern and a transfer pattern on the adhesive surface between the transfer film and the layer to be transferred, it is possible to increase the adhesion of the transfer film to the layer to be transferred by the anchor effect and to immerse it in a chemical solution. It is possible to prevent the transfer film from being peeled off from the transferred layer in a subsequent process, and it is possible to prevent the chemical solution from entering between the transfer film and the transferred layer in such a process.

Further, the laminated film of the present invention may have a configuration in which an arithmetic average roughness (Ra) of the uneven pattern formed on the outer resin layer is 0.2 μm to 2.5 μm.
According to the said structure, the adhesive force with respect to the to-be-transferred layer of a transfer film becomes appropriate.

In addition, the laminated film of the present invention may have a configuration in which a variation in arithmetic average roughness of the concavo-convex pattern formed on the outer resin layer is 0.50 μm or less.
According to the said structure, the adhesive force in each part of the adhesion surface with respect to the to-be-transferred layer of a transfer film can be stabilized by forming in 0.50 micrometer or less.

In the laminated film of the present invention, the transfer film is one in which the outer resin layer is laminated on both surfaces of the inner resin layer by extrusion lamination, and irregularities are formed on at least one surface of two rolls. Concavities and convexities may be formed on the outer resin layer by pressing with a roll.
According to the said structure, the laminated body by which the outer side resin layer was laminated | stacked on both surfaces of the inner side resin layer by extrusion lamination is formed by pressing with two rolls in which the unevenness | corrugation was formed in at least one roll surface. This reduces variations in the unevenness pattern of the outer resin layer and the arithmetic average roughness of the transfer pattern of the transferred layer formed by the uneven pattern, and stabilizes the adhesive force and peeling force between the transfer film and the transferred layer. Can be made. Moreover, according to the said structure, the adhesive force of the transfer film with respect to a to-be-transferred layer falls remarkably when mounting the said laminated | multilayer film on a printed wiring board, and heating and pressurizing. Thereby, the operation | work which peels a transfer film from a to-be-transferred layer becomes easy.

In the laminated film of the present invention, the transfer layer includes a conductive adhesive layer, a metal layer laminated on the conductive adhesive layer, and a protective layer laminated on the metal layer. The protective layer in the shield film having may be used.
According to the transfer film having the above-described configuration, the transfer film is prevented from being deformed, and thus can be easily laminated on the shield film. Furthermore, since the transfer film has good embedding properties, it is possible to reduce the formation of voids when embedding the conductive adhesive in the exposed portion of the ground wiring pattern of the insulating film of the printed wiring board, It is possible to reduce a decrease in conduction with the ground wiring pattern.

In the laminated film of the present invention, the transfer layer may be the protective layer in a shield film having a conductive adhesive layer and a protective layer laminated on the conductive adhesive layer. .
According to the said structure, since a deformation | transformation of a transfer film is prevented, lamination | stacking to a shield film can be performed easily. Furthermore, since the transfer film has good embedding properties, the formation of voids when embedding the conductive adhesive in exposed portions of the ground wiring pattern of the insulating film is reduced. It is possible to prevent a decrease in continuity with.

The shield printed wiring board of the present invention is characterized in that the shield film is bonded to a printed wiring board.
According to the above configuration, when the shield film is bonded to a printed wiring board and heated and pressed, it is possible to prevent the occurrence of problems due to deformation of the laminated film and to peel the transfer film from the protective layer. A shielded printed wiring board that is easy to work is obtained.

It is explanatory drawing of the laminated | multilayer film of this embodiment. It is explanatory drawing which shows the manufacturing method of the transfer film of this embodiment. It is explanatory drawing which shows embedding of the conductive adhesive to the ground circuit of the shield printed wiring board using the laminated film of this embodiment. It is explanatory drawing which shows embedding of the conductive adhesive to the ground circuit of the shield printed wiring board using the laminated film of this embodiment. It is explanatory drawing which shows the shield printed wiring board of the state which peeled the transfer film of this embodiment. It is explanatory drawing which shows the shield flexible printed wiring board of an Example. It is explanatory drawing of the test method of the evaluation test which concerns on peeling strength.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(Configuration of laminated film 1)
The laminated film 1 shown in FIG. 1 has an inner resin layer 62 and outer resin layers 63 and 63 laminated on one surface and the other surface of the inner resin layer, respectively, and at least one of these outer resin layers 63 and 63. The transfer film 6 having the concavo-convex pattern 61 formed on the outer surface of the transfer film 6 and the transfer film 6 having the transfer pattern 71 formed by the concavo-convex pattern 61 formed on the outer surface of the transfer film 6 on which the concavo-convex pattern 61 is formed are peelable. Layer 7. Moreover, in this embodiment, the transfer film 6 and the to-be-transferred layer 7 are laminated | stacked through the mold release layer 6b formed by apply | coating a mold release agent.

  The inner resin layer and the outer resin layer may be adhered by an adhesive, or may be laminated by heat fusion or the like without using an adhesive, but when laminated by thermal fusion, The laminated film with good adhesion between the inner resin layer and the outer resin layer can be easily produced by extrusion lamination. The two outer resin layers are preferably formed with the same layer thickness, but are not limited thereto.

(Transfer film 6)
As shown in FIG. 1, the transfer film 6 has outer resin layers 63 and 63 laminated on one surface and the other surface of the inner resin layer 62, respectively. In the present embodiment, the inner resin layer 62 is formed of PET (polyethylene terephthalate) resin, and the outer resin layers 63 and 63 are both formed of PBT (polybutylene terephthalate) resin. Here, Table 1 shows a comparison of general physical properties and characteristics of the PBT resin and the PET resin.

As shown in Table 1, it can be seen that PBT resin and PET resin are materials having very similar physical properties, molding properties, and mechanical properties.
Accordingly, the inner resin layer 62 is formed of PET resin and the outer resin layers 63 and 63 are both formed of PBT resin. For example, even when the temperature change occurs in the transfer film 6, the outer resin layers 63 and 63 are formed. Similarly, since it contracts and expands, it is possible to prevent deformation such as curling. Further, since the outer resin layer 63 is made of PBT resin, the shape is easily changed when pressure or the like is applied. That is, the outer resin layer 63 can easily follow the shape change of the laminated transfer target layer, and can obtain a good embedding property.

  In addition, by using the resin of the inner resin layer 62 and the outer resin layer 63 after crystallization, the deformation of the transfer film 6 can be reduced by reducing the thermal shrinkage rate.

  The material of the inner resin layer 62 is preferably PET resin, and the material of the outer resin layer 63 is preferably PBT resin, but is not limited thereto. In addition to this, examples of the material of the outer resin layer 63 include polyethylene naphthalate, polyimide, polyethylene, polypropylene, polyvinyl chloride, nylon, polycarbonate, and polymethylpentene. Examples of the material of the inner resin layer 62 include polypropylene and polymethylpentene. , Polyethylene naphthalate, and polyimide. The lower limit of the layer thickness of the inner resin layer 62 is preferably 6 μm, more preferably 8 μm, and even more preferably 25 μm. The upper limit is preferably 50 μm, more preferably 38 μm. The lower limit value of the thickness of the outer resin layer 63 is preferably 6 μm, and more preferably 8 μm. The upper limit is preferably 30 μm, more preferably 20 μm, and even more preferably 12 μm.

  Further, as shown in FIG. 1, a plurality of concave and convex patterns 61 (convex portions 61 a and concave portions 61 b) having a plurality of concave and convex shapes are formed on the entire surface of the outer resin layer 63 and the layer 7 to be transferred. Yes.

(Transfer film 6: production method)
Here, the manufacturing method of the transfer film 6 is demonstrated. The transfer film 6 is formed by laminating an outer resin layer 63 on both surfaces of the inner resin layer 62 by extrusion lamination, and is formed by pressing with two rolls having irregularities formed on at least one surface.
Specifically, first, the PET resin is extruded by an extruder (discharge width 1300 mm) set at a temperature of 280 ° C. to 290 ° C. to form the inner resin layer 62 in a film shape, and wound around a roll. Then, as shown in FIG. 2, the inner resin layer roll 21 wound with the PET resin is used as a supply, and the arithmetic average roughness of the inner resin layer 62 formed in a film shape is 0.2 μm to 2.5 μm. It supplies between the formed embossing roll 23 and the casting roll 24. FIG. On the other hand, while extruding PBT by two film extruders 22 and 22 (effective extrusion width 1300 mm) set at a temperature of 220 ° C. to 260 ° C., the extruded film-like outer resin layers 63 and 63 are respectively formed as inner resin layers. It is supplied between the embossing roll 23 and the casting roll 24 so as to be laminated on one side and the other side of 62. The laminated body of the inner resin layer 62 and the outer resin layers 63 and 63 is pressed between the embossing roll 23 and the casting roll 24, and the outer surface of the outer resin layer 63 laminated on the embossing roll 23 side has an arithmetic operation. The uneven pattern 61 having an average roughness of 0.2 μm to 2.5 μm is formed. In this manner, the transfer film 6 in which the outer resin layers 63 and 63 (PBT) are laminated on both surfaces of the inner resin layer 62 (PET resin) can be formed, and the uneven pattern 61 can be formed on the transfer film 6. The transfer film 6 formed in this way is wound around a transfer film roll 25 and stored. The outer resin layer 63 may be laminated one by one with one film extruder 22.
In FIG. 2, a cooling roll or the like is omitted, and cooling of the resin after extrusion, molding of an end portion of the film-like resin, and the like are appropriately performed.
Moreover, the said manufacturing method may be changed suitably by material, a design, etc.

The uneven pattern 61 is preferably formed on the entire outer surface of the outer resin layer 63, but is not limited thereto. Moreover, the aspect of the uneven | corrugated pattern 61 is not limited, For example, a predetermined pattern may be repeatedly formed and an unevenness | corrugation may be formed at random. Moreover, when the uneven | corrugated pattern 61 is formed in both the two outer side resin layers 63 * 63, it is good also as laminating with the two embossing rolls 23. FIG.
In order to reduce unevenness of unevenness in manufacturing lots for uneven pattern formation, embossing roll processing that allows a predetermined shape to be continuously formed by unevenness formed on the embossing roll is more effective than sandblasting and chemical matte coating. preferable. Also, when a shield film using an embossed roll processed transfer film is placed on a printed wiring board and heated and pressed to produce a shield printed wiring board, the adhesive strength of the transfer film to the transferred layer is large. descend. Thereby, the operation | work which peels a transfer film from a to-be-transferred layer becomes easy.

(Transfer layer 7)
As shown in FIG. 3, in this embodiment, the transferred layer 7 is laminated on the conductive adhesive layer 8a, the metal layer 8b laminated on the conductive adhesive layer 8a, and the metal layer 8b. A protective layer in a shield film having a protective layer. That is, the transferred layer 7 is a protective layer made of a cover film or an insulating resin coating layer.
Examples of the material constituting the cover film include polyester, polybenzimidazole, aramid, polyimide, polyimideamide, polyetherimide, polyphenylene sulfide (PPS), and polyethylene naphthalate (PEN).
An inexpensive polyester film is preferable when heat resistance is not required, and a polyphenylene sulfide film is preferable when flame resistance is required, and an aramid film or a polyimide film is preferable when heat resistance is required.
The insulating resin may be any resin having insulating properties, and examples thereof include a thermosetting resin and an ultraviolet curable resin. Examples of the thermosetting resin include a phenol resin, an acrylic resin, an epoxy resin, a melamine resin, a silicone resin, and an acrylic modified silicone resin. Examples of the ultraviolet curable resin include epoxy acrylate resins, polyester acrylate resins, and methacrylate-modified products thereof. The curing form may be any of thermosetting, ultraviolet curing, electron beam curing, etc., as long as it can be cured.
The outer resin layer 63 is preferably colored by adding a pigment (for example, white) at the time of melting the resin from the viewpoint of preventing forgetting to peel due to being colorless and transparent.
The lower limit of the thickness of the transferred layer 7 is preferably 1 μm, more preferably 3 μm, and even more preferably 5 μm. Further, the upper limit of the thickness of the transferred layer is preferably 15 μm, more preferably 10 μm, and even more preferably 7 μm. The transferred layer 7 is not limited to the protective layer of the shield film, and can be used for films such as a cover film and an antiglare film.

  Further, the transferred layer 7 is not limited to a single layer structure, and may have a multiple layer structure. For example, it may have a two-layer structure formed by sequentially coating a hard layer on the transfer film 6 side made of a resin excellent in wear resistance and blocking resistance and a soft layer made of a resin excellent in cushioning properties. .

In this embodiment, the transfer layer 7 is formed by coating the release layer 6b on one side of the transfer film 6 (the surface of the outer resin layer 63 on which the concavo-convex pattern 61 is formed), and then using the resin used for the transfer layer 7. Formed by coating. Thereby, in a state where the transfer layer 7 is detachably laminated on the transfer film 6, the concave / convex pattern 61 of the transfer film 6 is transferred to the transfer layer 7 to form the transfer pattern 71 (top portion 71 a, bottom portion 71 b). The That is, the bottom 71b of the transfer pattern 71 is formed by the protrusion 61a of the uneven pattern 61, and the top 71a of the transfer pattern 71 is formed by the recess 61b of the uneven pattern 61 (see FIG. 1).
More specifically, in a state where the transfer layer 7 is detachably laminated on the transfer film 6, the convex portion 61 a of the concave / convex pattern 61 engages with the bottom portion 71 b of the transfer pattern 71, and the concave portion 61 b of the concave / convex pattern 61. Engages with the top 71 a of the transfer pattern 71. As a result, the adhesion of the transfer film 6 to the transferred layer 7 can be enhanced by the anchor effect, and the transfer film 6 can be prevented from peeling off from the transferred layer 7 in a general post-process such as being immersed in a chemical solution. In such a process, the chemical liquid can be prevented from entering between the transfer film 6 and the transfer layer 7.
The arithmetic average roughness of the surface of the transfer layer 7 on which the transfer pattern 71 is provided after the transfer film 6 is peeled off is preferably 0.2 μm to 2.5 μm, and more preferably 0.5 μm. ˜1.7 μm is preferred. If the thickness is smaller than 0.2 μm, the transfer film may have too little adhesive force with respect to the transfer layer, and the transfer film may be peeled off from the transfer layer in a general post-process such as immersion in a chemical solution. When the thickness is larger than 2.5 μm, when the transfer film is peeled off from the transferred layer, the transferred layer itself may be broken by an excessively large adhesive force. Further, the variation of the arithmetic average roughness of the surface of the transferred layer 7 on which the transfer pattern 71 is provided after the transfer film 6 is peeled off may be 0.50 μm or less. When the variation of the arithmetic average roughness is 0.50 μm or less, the adhesive force at each part of the adhesive surface between the transfer film 6 and the transferred layer 7 can be stabilized.
In addition, as a method for forming the transfer layer 7 on one side of the transfer film 6, coating is preferable, but as a layer forming method other than coating, lamination, extrusion, dipping, or the like may be used.

(Release layer 6b)
The release layer 6b is not particularly limited as long as the transfer film 6 is peelable from the transfer layer 7, and a silicon-based or non-silicon-based release agent can be used. The maximum value of the thickness of the release layer 6 b is preferably smaller than the height of the uneven pattern 61 in the transfer film 6. When the release agent is coated on the uneven transfer film 6, the release agent accumulates in each recess in the uneven pattern 61, and the release agent is naturally dispersed in the transfer film 6. That is, the release agent is naturally dispersed in the process of laminating the transfer layer 7 and can be arranged substantially uniformly on the surface of the transfer film 6. Accordingly, the adhesive force of the transfer film 6 to the transferred layer 7 is suppressed to such an extent that the transferred layer 7 itself is not broken by an excessively large adhesive force when the transfer film 6 is peeled off from the transferred layer 7. be able to. Thus, since the adhesive force of the transfer film 6 to the transferred layer 7 can be appropriately controlled, it is possible to prevent problems caused by bonding with an excessively large adhesive force or a small adhesive force.
Further, the peeling strength of the transfer film 6 with respect to the transferred layer 7 when the transfer film 6 is peeled off from the transferred layer 7 is preferably 1 N / 50 mm to 20 N / 50 mm before heating and pressurization. When the peel strength value is less than 1 N / 50 mm, the transfer film 6 is peeled off from the transferred layer 7 when immersed in a chemical solution, while the peel strength value is greater than 20 N / 50 mm. This is because the adhesion force of the separate film (transfer film 6) to the transfer layer 7 is too strong, and when the transfer film 6 is peeled off, the transfer layer 7 is peeled off and the transfer layer 7 is torn. Further, the peel strength with respect to the transferred layer 7 after performing the heat press for attaching the shield film to the printed wiring board is preferably 0.2 N / 50 mm to 3.0 N / 50 mm, and moreover, 0 .2 N / 50 mm to 1.0 N / 50 mm is preferable. When the peel strength value is smaller than 0.2 N / 50 mm, the transfer film 6 may be naturally peeled off from the transferred layer 7 after hot pressing, while the peel strength value is 3.0 N / 50 mm. When the value is larger, workability when a person or a manufacturing apparatus peels the transfer film from the transfer layer is deteriorated.
In this embodiment, the transfer film 6 and the transferred layer 7 are laminated via the release layer 6b, but the present invention is not limited to this, and is laminated via a resin having a releasing property. Also good. Or you may laminate | stack without using a mold release agent. In the case where no releasable resin or release agent is used, any of the outer resin layers may be formed of a material to which a release agent is added.

  Here, the peel strength of the transfer film 6 with respect to the transferred layer 7 in the state before heating and pressurization is measured as follows. Specifically, as shown in FIG. 7, a double-sided tape is attached to the surface of the conductive adhesive layer 8a of the shield film 10 before pressing (before heating / pressing), and one side of the double-sided tape is attached to a testing machine (PALMEK). The shield film 10 is fixed to a base of a PFT-50S peel strength tester. And the edge part of the transfer film 6 of the shield film 10 is set to the chuck | zipper (illustration omitted) of a testing machine, and the peeling strength with respect to the to-be-transferred layer 7 of the transfer film 6 is measured. Here, as peeling conditions, as shown in FIG. 7, the peeling angle is 170 °, and the peeling speed of the transfer film 6 by the chuck is 1000 mm / min. Then, the test is performed 5 times, and the maximum value and the minimum value of the peel strength values obtained at each time are calculated as the peel strength values.

(Shield flexible printed wiring board 100)
3 is formed on the base film 2 and is covered with an insulating film 4 except for at least a part (non-insulating portion) 3c of the ground circuit 3b in the printed circuit 3 including the signal circuit 3a and the ground circuit 3b. It is explanatory drawing which shows the state which has mounted the shield film 10 on the base film 5, and is pressurizing, heating in a layer direction with a press machine.

  Here, the base film 2 and the printed circuit 3 may be joined with an adhesive or may be joined with a so-called non-adhesive copper-clad laminate that does not use an adhesive. Further, the insulating film 4 may be bonded to a flexible insulating film using an adhesive, or may be formed by a series of techniques such as coating of a photosensitive insulating resin, drying, exposure, development, and heat treatment. . Furthermore, the base film 5 includes a single-sided FPC having a printed circuit only on one side of the base film, a double-sided FPC having a printed circuit on both sides of the base film, and such an FPC (flexible printed wiring board). Multi-layer FPC with multiple layers, Flexboard (registered trademark) with multi-layer component mounting part and cable part, Flex-rigid board with rigid members constituting the multi-layer part, or TAB for tape carrier package A tape or the like can be employed as appropriate.

  The shield film 10 includes a transfer film 6 and a shield film body 9. The shield film main body 9 has a transfer layer 7 formed by coating on the transfer film 6 and an adhesive provided on the surface of the transfer layer 7 opposite to the surface in contact with the transfer film 6 via a metal layer 8b. And an agent layer 8a. Here, the electromagnetic wave shielding layer 8 is formed by the adhesive layer 8a made of a conductive adhesive and the metal layer 8b. In this electromagnetic wave shielding layer 8, when pressure is applied to the adhesive layer 8a softened by heating, the adhesive flows into the insulation removing portion 4a as indicated by an arrow, and conducts with the ground circuit 3b (see FIG. 3). Thus, in this embodiment, although it is the structure by which the conductive adhesive layer 8a is connected to the ground circuit 3b of the base film 5 (printed wiring board), it is not limited to this, A conductive adhesive layer does not necessarily need to be. It is not necessary to be connected to the ground of the printed wiring board.

When the above-described deformation of the adhesive layer 8a occurs, as shown in FIG. 4, a force is applied to the metal layer 8b in a direction following the deformation of the adhesive layer 8a, and the metal layer 8b is deformed. Then, a force is applied in the same direction in the order of the transferred layer 7, the outer resin layer 63 on which the concave / convex pattern 61 is formed, the inner resin layer 62, and the outermost outer resin layer 63, and deformation occurs. At this time, since the transferred layer 7 and the outer resin layer 63 are bonded, the force resulting from the deformation of the transferred layer 7 is transmitted to the outer resin layer 63 satisfactorily. In addition, since the outer resin layer 63 is made of polybutylene terephthalate and the inner resin layer 62 is made of polyethylene terephthalate, the outer resin layer 63 can exhibit good followability to the deformation of the transferred layer 7. Thereby, since the whole laminated body which consists of the transfer film 6 and the to-be-transferred layer 7 can track the deformation | transformation of the adhesive bond layer 8a, it does not inhibit the deformation | transformation to the direction which flows into the insulation removal part 4a of the adhesive bond layer 8a. . That is, by using the transfer film 6 and the transferred layer 7, it is possible to prevent a gap from the adhesive layer 8 a from being formed in the insulating removal portion 4 a and to improve the embedding property.
Then, after the adhesive layer 8a is sufficiently bonded to the non-insulating portion 3c and the insulating film 4 of the ground circuit 3b to form the shield flexible printed wiring board 100, the transfer film 6 of the shield film 10 is removed from the release layer 6b (FIG. 1), a shielded FPC 101 shown in FIG. 5 in which a transfer pattern 71 is provided on the surface of the transferred layer 7 is obtained.

  Examples of the material constituting the base film 2 and the insulating film 4 include resins such as polyester, polybenzimidazole, polyimide, polyimideamide, polyetherimide, polyphenylene sulfide (PPS), and epoxy. An inexpensive polyester film is preferable when heat resistance is not required, and a polyphenylene sulfide film is preferable when flame resistance is required, and a polyimide film is preferable when heat resistance is required.

  Adhesive layer 8a is a thermoplastic resin such as polystyrene, vinyl acetate, polyester, polyethylene, polypropylene, polyamide, rubber, acrylic, etc., phenolic, epoxy, urethane as adhesive resin. , Melamine-based and alkyd-based thermosetting resins. In addition, a conductive adhesive in which a conductive filler such as metal or carbon is mixed with these adhesive resins to provide conductivity can also be used. In this way, the ground circuit 3b and the metal layer 8b can be reliably electrically connected by using the conductive adhesive. Moreover, you may use the anisotropic conductive adhesive which reduced the quantity of the conductive filler as a conductive adhesive. As described above, when an anisotropic conductive adhesive is used as the conductive adhesive, the film becomes thinner than the isotropic conductive adhesive, and the amount of the conductive filler is small. Can do. Moreover, an isotropic conductive adhesive can also be used as a conductive adhesive. As described above, when an isotropic conductive adhesive is used as the conductive adhesive, the ground connection to the ground circuit 3b or the like can be achieved and the electromagnetic wave can be obtained only by providing a conductive adhesive layer with the isotropic conductive adhesive. A shield effect can be given. Further, when heat resistance is not particularly required, a polyester-based thermoplastic resin that is not restricted by storage conditions or the like is desirable. When heat resistance or better flexibility is required, the electromagnetic wave shielding layer 8 is provided. A highly reliable epoxy-based thermosetting resin after formation is desirable. Moreover, you may use the electroconductive adhesive which has adhesiveness at normal temperature for the adhesive bond layer 8a.

  Moreover, in the said embodiment, although the metal layer 8b and the adhesive bond layer 8a are used as the electromagnetic wave shielding layer 8, when an isotropic conductive adhesive is used as the adhesive bond layer 8a as mentioned above, a metal layer You may make the structure which excluded 8b.

  Examples of the conductive filler include silver-coated copper filler obtained by silver-plating carbon, silver, copper, nickel, solder, aluminum, and copper powder, and fillers obtained by metal-plating resin balls, glass beads, or the like. A mixture of Silver is expensive, copper lacks heat resistance reliability, aluminum lacks moisture resistance reliability, and solder is difficult to obtain sufficient conductivity. It is preferable to use a silver-coated copper filler or nickel having high reliability.

  The blending ratio of the conductive filler such as a metal filler to the adhesive resin depends on the shape of the filler and the like, but in the case of the silver-coated copper filler, 10 to 400 parts by weight with respect to 100 parts by weight of the adhesive resin. It is preferable that the amount be 20 to 150 parts by weight. If it exceeds 400 parts by weight, the adhesive force to the ground circuit (copper foil) 3b is lowered, and the flexibility of the shield FPC 101 is deteriorated. On the other hand, if the amount is less than 10 parts by weight, the conductivity is significantly lowered. Moreover, in the case of a nickel filler, it is preferable to set it as 40-400 weight part with respect to 100 weight part of adhesive resin, More preferably, it is good to set it as 100-350 weight part. If it exceeds 400 parts by weight, the adhesive force to the ground circuit (copper foil) 3b is lowered, and the flexibility of the shield FPC 101 is deteriorated. On the other hand, when the amount is less than 40 parts by weight, the conductivity is remarkably lowered. The shape of the conductive filler such as a metal filler may be any of a spherical shape, a needle shape, a fiber shape, a flake shape, and a dendritic shape.

  As described above, when the conductive filler such as a metal filler is mixed, the thickness of the adhesive layer 8a is increased by the amount of these fillers, and is about 20 ± 5 μm. Moreover, when not mixing a conductive filler, it is 1 micrometer-10 micrometers. For this reason, the electromagnetic wave shielding layer 8 can be made thin, and the thin shield FPC 101 can be obtained.

  Examples of the metal material forming the metal layer 8b include aluminum, copper, silver, and gold. The metal material may be appropriately selected according to the required shielding properties. However, copper has a problem that it is easily oxidized when exposed to the atmosphere, and gold is expensive. Therefore, inexpensive aluminum or highly reliable silver is used. preferable. The film thickness is appropriately selected according to the required shielding properties and flexibility, but is generally preferably 0.01 to 1.0 μm. When the thickness is less than 0.01 μm, the shielding effect is insufficient. On the other hand, when the thickness exceeds 1.0 μm, the flexibility is deteriorated. As a method for forming the metal layer 8b, there are vacuum deposition, sputtering, CVD, MO (metal organic), plating, and the like. However, in consideration of mass productivity, vacuum deposition is desirable, and an inexpensive and stable metal thin film can be obtained. it can. The metal layer is not limited to a metal thin film, and a metal foil may be used. In the case of a metal foil, the lower limit of the thickness of the metal foil is preferably 2 μm and more preferably 6 μm. Moreover, 18 micrometers is preferable and the upper limit of the thickness of metal foil has more preferable 12 micrometers.

  The embodiment of the present invention has been described above, but only specific examples are illustrated, and the present invention is not particularly limited, and the specific configuration and the like can be appropriately changed in design. In addition, the actions and effects described in the embodiments of the present invention only list the most preferable actions and effects resulting from the present invention, and the actions and effects according to the present invention are described in the embodiments of the present invention. It is not limited to things.

Next, this invention is demonstrated concretely using the Example and comparative example of the laminated film which concern on this embodiment.
As an example, a shield film 10 having a transfer film 6 and a shield film body 9 having a transfer layer 7 laminated on one of the outer resin layers 63 as in the configuration shown in FIG. 1 was used. .
The transfer film 6 used in the examples was formed by extrusion lamination so that the total thickness was 57 ± 3 μm. Moreover, the uneven | corrugated pattern 61 used that whose arithmetic mean roughness Ra is 0.35 micrometer. Moreover, as the transfer film 6, a film having a tensile strength TD (lateral direction) or MD (longitudinal direction) of 220 to 225 MPa was used. In addition, the transfer film 6 used has a shrinkage rate test result after heat treatment of 170 ° C. × 10 minutes, with a shrinkage rate of TD of 0% and MD of 0.7%.

Specifically, a method for producing the transfer film 6 used in the examples will be described. For the outer resin layers 63 and 63, PBT resin (trade name “Duranex (registered trademark)”) manufactured by Wintech Polymer Co., Ltd. was used. For the inner resin layer 62, a 25 μm thick PET resin (trade name “Embret (registered trademark)”) manufactured by Unitika Ltd. was used.
First, as shown in FIG. 2, the biaxially stretched PET film wound around the inner resin layer roll 21 is guided to a transfer film roll 25. On the other hand, the film extruders 22 and 22 are charged with the PBT resin, and are melt kneaded and adjusted in an extruder set at 235 ± 5 ° C. And PBT resin is extruded from the T die (flat extrusion port) (effective extrusion width 1300 mm) of the film extruders 22 and 22 to both sides of the PET resin so that the resin thickness is about 16 ± 3 μm. .
Thus, the transfer film 6 in which the PBT resin was extruded on both sides of the PET resin was received by the rotating embossing roll 23 and the casting roll 24, and film formation was performed. At this time, the temperature of the embossing roll 23 and the casting roll 24 was adjusted to 130 ± 3 ° C. The embossing roll 23 and the casting roll 24 had a roll diameter of 500 mm and a peripheral speed of 20 m / min. After the film was formed, the transfer film 6 was gradually cooled at a rate of 10 ° C./second to change from amorphous to crystalline, and then wound around a transfer film roll 25.

The transfer film 6 produced in this way was molded to a width of 1200 mm and used as the transfer film of the examples.
In the comparative example, a PET film having a layer thickness of 50 μm subjected to sandblasting with a width of 1200 mm was used as the transfer film.

As shown in FIG. 6, a transfer layer having a layer thickness of 5 to 7 μm is provided on the transfer films 206 of the above-described examples and comparative examples through a release layer (not shown) of about 0.6 μm. A shield film 210 was manufactured by laminating a shield film body 209 including a metal layer 208b, which is a metal thin film having a layer thickness of about 0.1 μm, and a conductive adhesive layer 208a having a layer thickness of about 16 μm.
The layer to be transferred 207 has a two-layer structure in which a transparent resin layer is provided on the side to which the transfer pattern is transferred by the transfer film 206, and a black resin layer is laminated on the transparent resin layer.

(Evaluation of transfer film in Examples)
In this manufacturing process, curling and shrinkage did not occur in the transfer film of the example, and the handling property was good. In addition, since one surface (outer resin layer) of the transfer film has a concavo-convex pattern (mat-processed), the transfer film is slippery and the finish of the coating winding can be improved.

(Evaluation of embeddability)
As shown in FIG. 6, the base film 205 is formed by laminating two printed circuits 203 of 55 μm thick copper foil on a polyimide base film 202 having a layer thickness of 25 μm with a sufficient space between them. A polyimide insulating film 204 having a thickness of 50 μm is laminated. Note that the sufficient distance means that the conductive adhesive layer 208a does not reach the printed circuit 203 even if the conductive adhesive layer 208a flows into the gap 213 when the shield film 210 is heated and pressed. At a given interval. Each insulating film 204 is formed with an insulating removal portion (through hole) 204a so that a part of the printed circuit 203 is exposed. About the case where the diameter of this insulation removal part 204a is 0.5 mm, 0.8 mm, and 1.0 mm, after heat-pressing the shield film of an Example and a comparative example, between two printed circuits 203 Table 2 shows the results of measuring the resistance value three times.

  As shown in Table 2, in the example, the connection resistance value is lower than that in the comparative example regardless of the diameter of the insulation removal portion 204a, and the printed circuits are easily conducted. That is, in the embodiment, the resistance value is lowered because more conductive adhesive layers 208a flow into the insulation removing portion 204a and reach the printed circuit 203 than in the comparative example, and the good embedding property is achieved. Was found to be obtained.

(Evaluation of surface roughness)
The shield film 210 of an Example and a comparative example shown in FIG. 6 is used. Each test piece has a rectangular shape with a length of 200 mm and a width of 50 mm.
The surface roughness (Ra (μm)) in Comparative Examples and Examples was measured with an ultradeep shape measuring microscope VX-8550 (KEYENCE). The measurement conditions were based on JIS B0601 (1994), the objective lens was 20 times, and the measurement pitch in the thickness direction was 0.2 μm.
Specifically, after winding the shield film 210 around a reel, five test pieces (n = n = 3) are respectively obtained from three locations in the flow direction (MD direction) (start portion, 1000 m (intermediate portion), 2000 m (final portion)). 5) was collected (15 test pieces in total), and the arithmetic average roughness (Ra) was measured with an ultradeep shape measuring microscope VX-8550 (KEYENCE). As a measurement value, an average value, a maximum value, and a minimum value of five test pieces at each location in the flow direction were obtained. Further, the difference between the maximum value and the minimum value of the 15 test pieces was defined as a variation in arithmetic average roughness. The results are shown in Table 3.

  The arithmetic average roughness variation (0.38 μm, 0.31 μm, 0.35 μm) of the example is significantly smaller than that of the comparative example (085.μm, 0.73 μm, 0.73 μm). The reason for this is considered to be that the uneven pattern formed on the roll is repeatedly formed on the outer resin layer 63 of the transfer film 6 in the processing with the embossing roll, so that the uneven pattern is constant. For this reason, an Example can stabilize the adhesive force and peeling force in each part of the adhesive surface of the transfer film 6 and the to-be-transferred layer 7 rather than the comparative example using sandblasting.

(Evaluation of peelability before heating)
The peel strength of the transfer film 6 with respect to the transferred layer 7 in the state before the heating press is measured as follows. Specifically, a test piece having a width of 50 mm and a length of 200 mm was sampled from the shield film 210 of the comparative example and the example shown in FIG. 6, and this test piece was used as the shield film 10. As shown in FIG. A double-sided tape is affixed to the surface of the conductive adhesive layer 8a, and one side of the double-sided tape is affixed to the base of a tester (PALMEK PFT-50S peel strength tester) to fix the shield film 10. And the edge part of the transfer film 6 of the shield film 10 is set to the chuck | zipper of a testing machine, and the peeling strength with respect to the to-be-transferred layer 7 of the transfer film 6 is measured. Here, as peeling conditions, as shown in FIG. 7, the peeling angle is 170 °, and the peeling speed of the transfer film 6 by the chuck is 1000 mm / min. As the number of tests, the comparative example and the example were each performed five times, and the maximum value and the minimum value were calculated for each time. The results are shown in Table 4.
Moreover, the evaluation criteria of peelability are as follows. Specifically, peeling of the transfer film when immersed in a chemical solution was confirmed before heating press (no peeling: ◯, with peeling: x). Further, it was confirmed whether or not the transfer layer 7 was torn when the transfer film 6 was peeled off from the transfer layer 7 before heating press (no tear: ◯, with tear: x). Further, it was confirmed whether or not the transfer film 6 was torn after the heating press (no tear: ◯, with tear: x). Moreover, workability | operativity at the time of peeling the transfer film 6 after the heat press from the to-be-transferred layer 7 was confirmed (good: (double-circle), normal: (circle), bad: x).

(Evaluation of peelability after heating)
On the other hand, the peel strength of the transfer film 6 with respect to the transferred layer 7 in the state after the heat press is measured as follows. The surface of the conductive adhesive layer 208a of the shield film 210 according to the comparative example and the example is thermocompression bonded to the polyimide surface side of a copper clad laminate having a polyimide surface and a copper foil surface by a press. As thermocompression bonding conditions in the press machine at this time, the pressure is preferably 2 to 5 MPa, the temperature is 140 to 180 ° C., and the time is preferably 3 to 60 minutes. In this measurement, thermocompression bonding is performed by setting the set temperature to 170 ° C., applying a load for 60 sec at 0.5 MPa, and then applying a load for 180 sec at 3.0 MPa.
Then, a double-sided tape is affixed to the copper foil side of the copper clad laminate on which the shield film 210 is thermocompression bonded, and one side of the double-sided tape is attached to a test machine stand (PALMEK PFT-50S peel strength tester) as shown in FIG. ) And the shield film 210 is fixed. After that, the value of the peel strength is calculated in the same manner as the test method described in the measurement of the peel strength before pressing.

As shown in Table 4, in the state after the heat press, the maximum value and the minimum value of the examples in the five peel tests are 0.88 N / 50 mm and 0.29 N / 50 mm, respectively. The maximum value and the minimum value are 2.94 N / 50 mm and 1.37 N / 50 mm, respectively, and the variation in the example is smaller than that in the comparative example. Thereby, after heat pressing, workability is improved when the transfer film is peeled off from the transferred layer.
Moreover, as shown in Table 4, when the peeling force of an Example and a comparative example is compared, a big difference is not recognized between an Example and a comparative example before a heat press (before the heat press of an Example: Maximum value 5.34 N / 50 mm, minimum value 3.78 N / 50 mm, before heating press of comparative example: maximum value 5.88 N / 50 mm, minimum value 3.92 N / 50 mm), after heating press, the example is better Peeling force is remarkably smaller than that of the comparative example (after the heat-press of the example: maximum value 0.88 N / 50 mm, minimum value 0.29 N / 50 mm, after the heat-press of the comparative example: maximum value 2.94 N / 50 mm, minimum value : 1.37 N / 50 mm). Specifically, when paying attention to the maximum value of the peeling force, the comparative example is reduced to about 1/2 after the heat press, whereas the example is reduced to about 1/6. ing. In this way, the embodiment prevents the peeling in a general post-process such as immersion in a chemical solution because the transfer film has a high adhesive force to the transferred layer before the hot press, and the adhesive after the hot press The workability at the time of peeling off the transfer film by significantly reducing the force can be improved.

DESCRIPTION OF SYMBOLS 1 Shield film 2 Base film 2a Insulation removal part 3 Printed circuit 3a Signal circuit 3b Ground circuit 3c Non-insulation part 4 Insulation film 4a Insulation removal part 5 Base film 6 Transfer film 6b Release layer 7 Transferred layer 8 Electromagnetic wave shielding layer 8a Adhesion Agent layer 8b Metal layer 9 Shield film body 10 Shield film 21 Roll for inner resin layer 22 Film extruder 23 Emboss roll 24 Casting roll 25 Transfer film roll 61 Concave and convex pattern 61a Convex part 61b Concave part 71 Transfer pattern 71a Top part 71b Bottom part 100 Shield Flexible printed wiring board 101 Shield flexible printed wiring board

Claims (7)

A crystallized inner resin layer, and a crystallized outer resin layer laminated on one surface and the other surface of the inner resin layer, and an uneven pattern is formed on at least one outer surface of the outer resin layer. A formed transfer film;
The transfer film is detachably laminated on the outer surface of the transfer film on which the concavo-convex pattern is formed, and has a transfer layer on which the transfer pattern by the concavo-convex pattern is formed. And the outer resin layer is made of polybutylene terephthalate.   The laminated film according to claim 1, wherein an arithmetic average roughness of the uneven pattern formed on the outer resin layer is 0.2 μm to 2.5 μm.   The laminated film according to claim 2, wherein a variation in arithmetic average roughness of the uneven pattern formed on the outer resin layer is 0.50 μm or less.   The transfer film is formed by laminating the outer resin layer on both surfaces of the inner resin layer by extrusion lamination, and is formed by pressing with a roll having irregularities formed on at least one surface of two rolls. The laminated film according to any one of claims 1 to 3, wherein: The transferred layer is
It is the said protective layer in the shield film which has a conductive adhesive layer, the metal layer laminated | stacked on the said conductive adhesive layer, and the protective layer laminated | stacked on the said metal layer, It is characterized by the above-mentioned. Item 5. The laminated film according to any one of Items 1 to 4. The transferred layer is
It is the said protective layer in the shield film which has a conductive adhesive layer and the protective layer laminated | stacked on the said conductive adhesive layer, The any one of Claims 1 thru | or 4 characterized by the above-mentioned. Laminated film.   A shield printed wiring board, wherein the shield film of claim 5 or 6 is bonded to a printed wiring board.

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